The "Captain Underpants Series" is a popular children's book series written by Dav Pilkey. It follows the adventures of two fourth-graders, George Beard and Harold Hutchins, who create a comic book superhero named Captain Underpants. The series is known for its humor, engaging illustrations, and playful storytelling, making it appealing to young readers. The books often feature themes of friendship, creativity, and the importance of imagination. Each story typically includes comic strips and silly antics, encouraging children to enjoy reading. The series has also been adapted into animated films and a television series, further expanding its reach and popularity.